One aspect relates to an ablation electrode for high-frequency ablation in medical technology, whereby the ablation electrode includes a gold alloy. One aspect relates to a catheter tip for use with a catheter device, including an ablation electrode, as well as a catheter device for high-frequency ablation, including a catheter tip, as well as the use of an ablation electrode, a catheter tip or a catheter device for high-frequency ablation; as well as a process for production of an ablation electrode.
In catheter ablations, tissue emitting incorrect electrical pulses is specifically eliminated or scars are caused in tissue areas to interrupt the conduction of the incorrect pulses. In high frequency ablation, a catheter is introduced into the tissue and locally limited destruction by heat is caused by the heat developed by an applied high-frequency current. The destruction originates from an ablation electrode that is situated at the tip of the distal end of a catheter device. The heat is usually generated in the electrode by high-frequency waves with a frequency above 1 kHz. To assure sufficient heat dissipation during the treatment of the patient, catheter components often need to be optimised, through extensive design efforts, for sufficient heat dissipation, for example by means of cooling channels. U.S. Pat. No. 5,348,554 describes an ablation electrode designed to have an internal cooling for improved heat dissipation, because the component itself does not provide for sufficient heat dissipation.
Platinum-iridium alloys that are in general use in medical technology, in some cases palladium alloys as well, are used as electrode materials. With regard to catheter devices without cooling or catheter devices with passive cooling, it would be desirable to have alloys with a higher thermal conductivity than the aforementioned alloys.
U.S. Pat. No. 6,099,524 describes mapping and ablation catheter systems with electrodes based on gold, gold alloys, platinum, titanium, tungsten, stainless steel, and cobalt-based biocompatible materials. A gold-nickel alloy is specified therein, for example a gold-nickel alloy including 88% by weight gold and 12% by weight nickel. The alloy is said to comprise a higher thermal conductivity than platinum alloys and is therefore used as a heat-dissipating material at the catheter tip of an ablation catheter.
Alloys, such as AuNi12 or other gold-nickel alloys, attain their strength only by the process of solid solution strengthening. As a result, the alloys comprise heat conductivities that do not reach, or only minimally exceed, the thermal conductivity of pure platinum of 74 W/m*K. Other effective solidification mechanisms, such as precipitation hardening, are not known for the AuNi alloy system. As a result, it is not feasible to attain high mechanical strengths based on AuNi alloy systems.
Pure gold has a specific thermal conductivity of 320 W/m*K, but is difficult to process by means of cutting processes, such as turning, milling, and grinding, because its hardness is low. Ablative or erosive procedures, such as laser processing, usually require a holding device, which also is associated with problems related to the attachment to said holding devices in the case of soft materials like gold. As a result, it is not feasible to produce large quantities of ablation electrodes with thin walls on the basis of pure gold by means of these and similar processes in an economically reasonable manner.
But materials with a thermal conductivity as high as that of gold are desirable for application in ablation devices, for example, those with electrodes of low wall thickness, because the high thermal conductivity allows for effective heat dissipation even in the absence of active cooling. In addition, ablation electrodes with thin walls are desirable considering the ongoing trend towards miniaturisation in medical technology.
In general, embodiments overcome the aforementioned disadvantages, at least in part. Specifically, embodiments provide an ablation electrode that includes a high specific thermal conductivity and contains a material that can be produced and processed by means of cutting or erosive processes to have thin walls.